1. Department of Endodontology, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
2. Department of Dental Medicine, Division of Periodontology, Karolinska Institutet, Huddinge, Sweden
3. Department of Oral Maxillofacial Radiology, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden